For anyone curious, I put the 7" LAT on a scale (all mounting hardware is in there).
Less in the interest of comparing products, and more just because I haven't calibrated the kitchen scale and I had a known quantity available, I also give you a 7" MI Combat rail plus mounting hardware.
The weight of the LAT is definitely in the beefy mount up system. I mocked it up as a suppressed .22, and since the chamber area of the .22 barrel is a good size chunk of steel, it made the upper amusingly heavy right in the center. Not unfortunately, just amusingly.
Inspired by the 7", I placed an order tonight for a 13.2" as well.